In my last blog I discussed the impact that domestic gas prices could have on future energy budgets. Another key factor in determining energy usage, particularly for space heating, is the weather or more specifically, the outside temperature. Heating (and cooling) degree days are published and readily available on the internet and can be used to estimate future heating requirements. If the forthcoming year is mild then the heating load could be lower than the previous year, but conversely if there is a long, harsh winter then the heating load could be higher than the previous year. How much higher or lower will be difficult to predict accurately, but analysing previous year’s data will give an indication.
The pertinent question is whether or not your energy budget is flexible enough to cope with the uncertainty. To illustrate how flexible your budget might need to be, i.e. quantify the risk, I have used some gas consumption data from the Carbon Trust’s guide on degree days and used degree day data for Gatwick, downloaded from www.degreedays.net from August 2009.
I used linear regression to estimate the gas consumption in 2013 based on the average monthly degree days from 2009 and then compared this to the sum of the minimum monthly values and maximum monthly values for the same period. These values are presented in the Figure along with the Carbon Trust data: the model suggests that we should budget for around 3,500 MWh of gas next year. However, the swing attributed to extremes, e.g. a mild year or a harsh winter, is approximately ±20%.
Am I scaremongering here too? Again, not intentionally. My message is concerned about being prepared: a ±20% swing in energy spend might be an acceptable risk when compared to the cost of implementing an energy management system, but on the other hand it might not. You could get more degree day data and go further back to see if there is a downward trend and thus help to narrow the swing interval.
Nevertheless, there will always be some uncertainty – it’s the weather – and that introduces financial risk to the energy budget. If it is to be mitigated then it needs to be managed and that means it needs to be measured, to paraphrase Lord Kelvin. Can you afford not to be measuring and monitoring your gas consumption?
I used linear regression to estimate the gas consumption in 2013 based on the average monthly degree days from 2009 and then compared this to the sum of the minimum monthly values and maximum monthly values for the same period. These values are presented in the Figure along with the Carbon Trust data: the model suggests that we should budget for around 3,500 MWh of gas next year. However, the swing attributed to extremes, e.g. a mild year or a harsh winter, is approximately ±20%.
Am I scaremongering here too? Again, not intentionally. My message is concerned about being prepared: a ±20% swing in energy spend might be an acceptable risk when compared to the cost of implementing an energy management system, but on the other hand it might not. You could get more degree day data and go further back to see if there is a downward trend and thus help to narrow the swing interval.
Nevertheless, there will always be some uncertainty – it’s the weather – and that introduces financial risk to the energy budget. If it is to be mitigated then it needs to be managed and that means it needs to be measured, to paraphrase Lord Kelvin. Can you afford not to be measuring and monitoring your gas consumption?
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